Sandstone and cousins Soft shades, rich textures, durability, versatility: with all these qualities to recommend them, the stones shown here are an attractive alternative for indoor or outdoor paving. Rough or polished, split into random slabs or cut into tiles, they can create a look that varies from rugged to refined.

This earth-toned group--sandstone, limestone, quartzite, and volcanic rock--ranges from dusty pink to pale green to coffee tan. Compared to marble, granite, and slate, these four stones have a grainier surface and, except for quartzite, are generally softer in composition. They have comparable uses--including terraces, patios, or flooring--and the installation process is similar.

Sandstones and limestones are both sedimentary rocks, but sandstone is composed of sand-size grains naturally cemented by minerals. Limestone principally contains calcite or dolomite--sometimes both.

Quartzite is a variety of sandstone. Geologically speaking, it is metamorphic rock resulting from quartz sandstone that's been heated under pressure and then cooled, making it very hard.

The volcanic rock most often used for paving is technically tufaceous rhyolite that occurs in ashflows.

Stone yards that carry marble, granite, and slate also usually stock one or more of the kinds we discuss on these pages. Look in the yellow pages under Stone--Natural.

Sandstone: nonskid walking outdoors

New York's numerous brownstone row houses are one proof of sandstone's popularity in the 19th century. In the 1950s, pink and tan types became popular wall facings. Light-colored sandstones are making a comeback now--especially for outdoor terraces. This stone's gritty texture makes a good walking surface, even when it's wet.

Coming from Arizona, California, Colorado, Idaho, and Utah, most of the sandstone you'll see is colored light pink, dark pink, or buff. Sandstone comes in standard 6-, 12-, 18-, or 24-inch squares as well as "random" (undimensioned) sizes; thicknesses range from 1-1/2 to 2 inches. Random pieces are often called flagstones (technically a flagstone is any flat stone that is either naturally thin or split from rock that cleaves easily). Odd sizes are also available. Price ranges from $4 to $6 per square foot, not including installation.

Limestone: the marble look-alike

This stone was a favorite building material during the Renaissance. Limestone is generally characterized by its white to gray and beige colors and fine-grained patterns that often include fossils.

Some limestones can take a polish and are indistinguishable from marble. Limestone is quarried worldwide, with Indiana, Italy, and France current major sources.

Limestone generally comes in 12- and 18-inch-square tiles 3/8 and 5/8 inch thick, respectively, and in 4- by 8-foot slabs at least 3/4 inch thick. Several finishes are available: honed (cut but not polished), polished, and occasionally flamed (for a rough, uneven texture). Polished surfaces are slippery, especially when wet. Costs run about $9 to $15 per square foot.

Quartzite: hard, durable

This stone, which is harder than the others discussed here, resembles slate in its patterning and colors, though it is usually not as dark. The ground floor of the Monterey Bay Aquarium is paved in quartzite, whose rough, granite-like texture provides a skid-resistant surface.

Adoquin (Spanish for paving stone) is the generic name of a dense volcanic stone quarried extensively in Mexico and used to pave plazas throughout that country. Colors include pink, orange, gray, and tan. Texture is grainy to the touch, and the surface is slip resistant.

Standard-size pavers are 12 inches square or 8 by 16 inches. The commonest finishes are "sawcut," with a blade-cut surface and a uniform tile appearance, and "rustico," with a rough, hand-chiseled surface. Sawcut pavers are 3/4 inch thick, rustico 1-1/2 inches. At roughly $4 to $5 per square foot, adoquin is one of the most economical stone paver choices.